Citations

9532 Background: Both pembrolizumab (PEMBRO) and combination ipilimumab + nivolumab (IPI+NIVO) are FDA-approved immunotherapies for advanced melanoma (AM). These two treatment regimens have different toxicity profiles which may impact health care resource utilization (HCRU). Our aim was to compare real-world risk of hospitalization and emergency department (ED) visits within 12 months of starting the two treatment regimens. Methods: A retrospective cohort study was conducted in patients ≥18 years old with AM initiating PEMBRO or IPI+NIVO between Jan 1, 2016 – Dec 30, 2017. Patients were identified from 12 US academic medical centers and affiliated satellite clinics. Data were abstracted through chart review. All-cause hospitalizations or ED visits and the rates per patient per month (PPPM) through 12 months of follow-up were calculated. Utilization was compared between PEMRBO and IPI+NIVO using multivariate logistic regression analysis. Results: 400 patients were included, 200 each PEMBRO and IPI+NIVO with mean (SD) follow-up time of 10 (3) and 10 (4) months, respectively. The PEMBRO cohort had poorer Eastern Cooperative Group (ECOG) performance status at treatment start, 71% ECOG 0 or 1 vs 88% (p < .001); more diabetes, 21% vs 13% (p = .045); a trend towards more heart disease, 18% vs 12% (p = .067); were more likely to be PD-L1 expression positive, 77% vs 63% (p = .011); and less likely to harbor a BRAF mutation, 35% vs 50% (p = .003). The proportion with at least one hospitalization through 12 months was 17% PEMBRO vs 24% IPI+NIVO. Less than 2% of patients had more than one admission and none had more than two, regardless of cohort. Unadjusted mean (SD) PPPM hospitalizations were .016 (.037) for PEMBRO and .020 (.038) for IPI+NIVO. The adjusted odds ratio for any hospitalization with PEMBRO was 0.55 (95% CI .31, .97; p = .039) vs. IPI+NIVO. ED visits occurred in 18% vs 21% in PEMBRO and IPI+NIVO respectively, with no difference in covariate-adjusted analysis (p = .147). Conclusions: Patients receiving PEMBRO had a significantly lower probability of hospitalization and similar probability of ER visits compared with IPI+NIVO in the real world through 12 months.

6592 Background: Sex, age and ECOG performance status (PS) may affect immune response and the efficacy of cancer immunotherapy with immune checkpoint inhibitors (ICI). We did a meta-analysis to assess the potential sex, age and ECOG PS differences of immunotherapy efficacy in advanced cancer. Methods: PubMed was searched up to January 15, 2019 for randomized controlled trials (RCT) comparing overall survival (OS) in patients with advanced cancer treated with ICI immunotherapy vs control therapy (without ICI). For sex difference analysis, pooled hazard ratio (HR) of death for men and women was calculated separately, and the heterogeneity between the two estimates was assessed using an interaction test by pooling study-specific interaction HR. Age ( < 65 vs ≥65) and ECOG PS (0 vs ≥1) difference was analyzed similarly. Subgroup analysis by cancer type and line of therapy (frontline vs subsequent) was explored. All analyses were done in Comprehensive Meta Analysis (v2) with random effects models. Results: Thirty phase 2/3 RCTs involving 17,728 patients were included. An OS benefit of immunotherapy was found for both men (HR 0.75, 95% confidence interval [CI] 0.69-0.81, P < 0.01) and women (HR 0.79, 95% CI 0.69-0.90, P < 0.01); for both younger ( < 65; HR 0.75, 95% CI 0.68-0.83, P < 0.01) and older (≥65; HR 0.76, 95% CI 0.69-0.83, P < 0.01) patients; and for both ECOG PS 0 (HR 0.78, 95% CI 0.69-0.89, P < 0.01) and PS ≥1 (HR 0.77, 95% CI 0.71-0.84, P < 0.01) patients. No significant difference of relative benefit from immunotherapy over control therapy was found in patients with different sex ( P = 0.283), age ( P = 0.906) or ECOG PS ( P = 0.783). In melanoma RCTs, compared with women (HR 0.77, 95% CI 0.64-0.94, P < 0.01), men (HR 0.56, 95% CI 0.42-0.76, P < 0.01) had more OS benefit from immunotherapy ( P = 0.037). No significant difference was found in other subgroup analyses by cancer types or line of therapy. Conclusions: Overall we found no evidence of association of sex, age, or ECOG PS with cancer immunotherapy efficacy. However, in melanoma, men might benefit more from immunotherapy than women.

5574 Background: A noninvasive cell-free DNA (cfDNA)-based cancer detection assay offers the hope of a blood test that might reduce morbidity and mortality of cancers, particularly those without recommended screening tests (eg, some gynecologic cancers). CCGA (NCT02889978) is a prospective, multi-center, longitudinal, case-control study evaluating models for discriminating cancer versus non-cancer. Here, we report F/U of control participants (pts) who demonstrated a cancer-signal in CCGA. Methods: Clinically evaluable samples (N = 2508) from pts enrolled without a cancer diagnosis (dx; NC) and treatment-naive pts with newly diagnosed cancer (C) were divided into training (n = 1564; 580 NC, 984 C) and test (n = 944; 368 NC, 576 C) sets. Classification performance (cancer/non-cancer) was assessed via 3 prototype assays: whole-genome bisulfite (WGBS), whole-genome (WGS), and targeted (507 gene) sequencing. Notable outlier NC pts were identified with cancer-like scores in either ≥2 assay classification results or by the presence of known cancer drivers with ≥1 assay classification result suggesting cancer. All pts are currently in F/U in accordance with study protocol (to date: 80% with > 10 mo and 15% with > 22 mo F/U). Results: Among training and test sets, 8 ( < 1%) NC pts were identified with a cancer-like signal. To-date, 2 have been diagnosed with a gynecologic malignancy: 1 stage IIIc clear cell endometrial carcinoma and 1 stage IIIc ovarian cancer, 3 and 2 months (mo) post-enrollment [PE], respectively. Among C pts in the study, sensitivity (at 98% specificity; WGBS) in these cancer types was: uterine/endometrial: 11% (n = 27 train) and 22% (n = 9 test); ovarian: 82% (n = 17) and 71% (n = 7). In addition, a third NC pt was diagnosed with a stage IV lung cancer 15 mo PE. Conclusions: This cfDNA-based assay detected a cancer-like signal that anticipated a clinical presentation of cancer in undiagnosed pts as early as 15 months prior to the actual dx. High specificity ( > 99%) requires accounting for undiagnosed cancers in study design and analysis. Together, these data suggest that this prototype assay may have high performance detecting a variety of gynecological and other cancers. Clinical trial information: NCT02889978.

3049 Background: For multi-cancer detection using cfDNA, TOO determination is critical to enable safe and efficient diagnostic follow-up. Previous array-based studies captured < 2% of genomic CpGs. Here, we report genome-wide fragment-level methylation patterns across 811 cancer cell methylomes representing 21 tumor types (97% of SEER cancer incidence), and define effects of this methylation database on TOO prediction within a machine learning framework. Methods: Genomic DNA from 655 formalin-fixed paraffin-embedded (FFPE) tumor tissues and 156 isolated cells from tumors was subjected to a prototype 30x whole-genome bisulfite sequencing (WGBS) assay, as previously reported in the Circulating Cell-free Genome Atlas (CCGA) study (NCT02889978). Two independent TOO models, one with and one without the methylation database, were fitted on training samples; each was used to predict on the test set. A WGBS classifier was used to detect cancer at 98% specificity; reported TOO results reflect percent agreement between predicted and true TOO among those detected cancers (166 cases: 81 stage I-III, 69 stage IV, 16 non-informative). Results: Genome-wide methylation data generated from this database allowed fragment-level analysis and coverage of ~30 million CpGs across the genome (~60-fold greater than array-based approaches). Incorrect TOO assignments decreased by 35% (20% to 13%) after incorporating methylation database information into TOO classification. Improvement was observed across all cancer types and was consistent in early-stage cancers (stage I-III). Respective performances in breast cancer (n = 23) were 87% vs 96%; in lung cancer (n = 32) were 85% vs 88%; in hepatobiliary (n = 10) were 70% vs 90%; and in pancreatic cancer (n = 17) were 94% vs 100%. Results using an optimized approach informed by these results in a large cohort of CCGA participants will be reported. Conclusions: Incorporating data from a large methylation database improved TOO performance in multiple cancer types. This supports feasibility of this methylation-based approach as an early cancer detection test across cancer types. Clinical trial information: NCT02889978.

TPS2656 Background: ESCC remains the predominant histological subtype of, and accounts for most deaths from, esophageal cancer. PD-1 inhibition has demonstrated antitumor activity and was generally well tolerated in patients (pts) with advanced unresectable or metastatic ESCC. Tislelizumab, an investigational anti-PD-1 antibody, was engineered to minimize binding to FcγR on macrophages to abrogate antibody-dependent phagocytosis, a mechanism of T-cell clearance and potential resistance to anti-PD-1 therapy. Results from early phase clinical studies suggest single-agent tislelizumab was generally well tolerated and had antitumor activity in pts with solid tumors, including ESCC. Methods: This phase 3, randomized, placebo-controlled, double-blind study (NCT03783442) is designed to evaluate the efficacy and safety of tislelizumab plus chemotherapy as first-line treatment of unresectable, locally advanced recurrent or metastatic ESCC. Adult pts with histologically confirmed ESCC that had metastatic disease either at first diagnosis or with a ≥6 month treatment-free interval will be eligible. Additional eligibility criteria include measurable/evaluable disease, ECOG performance score ≤1, and no prior anti-PD-(L)-1, PD-L2, or other first-line therapy or palliative radiation treatment ≤4 weeks before treatment. Approximately 480 pts will be randomized 1:1 to receive investigator-chosen chemotherapy (ICC) plus tislelizumab 200 mg IV Q3W or ICC plus placebo. Chemotherapy options include: platinum (cisplatin 60–80 mg/m2 or oxaliplatin 130 mg/m2 IV Q3W) plus 5-FU 750–800 mg/m2 IV daily for 5 days Q3W; or platinum plus capecitabine 1000 mg/m2 orally BID for 14 days Q3W; or platinum + paclitaxel 175 mg/m2 IV Q3W. Progression-free survival and overall survival are coprimary endpoints; secondary endpoints include objective response rate, duration of response, and health-related quality-of-life. Safety will be assessed by monitoring adverse events, physical examinations, vital signs, and electrocardiograms. This study is actively enrolling. Clinical trial information: NCT03783442.

1562 Background: In Caucasian-predominant populations, overweight or obese NSCLC pts (BMI≥25-kg/m2) have better prognosis while underweight (BMI≤18.5-kg/m2) pts have a worse prognosis. A large pooled sample allowed us to evaluate the role of ethnicity in this BMI-NSCLC OS relationship. Methods: Using individual data, survival analysis was performed on 15 ILCCO studies, assessing the interactions between ethnicity and BMI on overall survival (OS). Adjusted Hazard Ratios (aHR) from Cox models and adjusted penalized smoothing spline plots were generated. Results: Among 13416 (77%) Caucasian, 2975 (17%) Asian, and 935 (5%) Black NSCLC pts analyzed, we confirmed that for all pts, being underweight at NSCLC diagnosis was associated with worse OS (aHR=1.68, CI 1.5-1.8, p<0.001), while overweight/obese pts had improved survival (aHR 0.89, CI 0.8-0.9, p<0.001), when compared to pts with normal BMI. In general, Black pts had poorer OS than Caucasian pts (aHR 1.26 CI 1.1-1.4, p<0.001). However, the BMI-OS relationship differed according to ethnicity (BMI-ethnicity interaction, p=0.009): Caucasian underweight pts had poorer OS (aHR 1.67, CI 1.5-1.8, P<0.001) while overweight/obese pts had improved OS (aHR 0.89, CI 0.8-0.9, P<0.001). In Asian pts, these two associations were aHR 1.15, CI 0.8-1.5, P=0.33, and aHR 0.91, CI 0.7-1.1, P=0.32, respectively. In Black pts, these two associations were aHR 1.06, CI 0.7-1.5, p=0.73 and 0.75, CI 0.6-0.8 p<0.001, respectively. For overweight/obese patients, as BMI rises from 25-kg/m2 through 45-kg/m2, the prognosis worsens for Caucasian pts, remains stable for Asian pts, but improves for Black pts. Conclusions: InCaucasian pts, being underweight had a greater negative impact on OS than for Asian or Black pts, while being obese had a greater beneficial impact in Blacks than in other ethnic groups. These ethnic differences likely reflect genetically-informed muscle/adipose tissue distributions, where Black pts may have less sarcopenic obesity than other ethnicities. In future prognostic studies, BMI relationships must account for ethnic differences.

1545 Background: Screening tests for early cancer detection are often criticized due to risk of overdiagnosis—detection of good prognosis cancers which may not require immediate treatment. We recently reported development of cfDNA sequencing approaches for cancer detection; longitudinal follow-up (F/U) data were utilized here to evaluate prognostic significance of cancer detection using cfDNA. Methods: Plasma cfDNA samples were subjected to whole-genome bisulfite sequencing (WGBS, 30X) as part of a previously-reported Circulating Cell-free Genome Atlas (CCGA; NCT02889978) substudy. This exploratory analysis evaluated the overall survival (OS) of training and test set participants (pts) with cancer (20 cancer types, any stage I-IV). Combining train and test set pts, univariate and multivariate analyses (Cox proportional hazards) assessed OS association with WGBS result (cancer detected vs not detected, set at 98% specificity), clinical stage (IV vs I-III), diagnostic method (symptom- vs screen-detected), sex, age, and histologic grade. Results: Of 827 pts from the training set with F/U (median 12.2 mo), 334 (40.4%) had WGBS-detected cancer. Among 127 (15.4%) pts with cancer that died during F/U, cancer was detected in 104 (81.9%). Results were similar in the test set. In univariate analyses all variables were associated with prognosis, including WGBS result (HR 7.7 p<0.001). In multivariate analyses accounting for other covariates, the three variables that most significantly remained prognostic were WGBS (HR 3.0, p<0.001), clinical stage (HR 3.3, p<0.001), and diagnostic method (HR 3.0, p<0.001). Validation of these findings is ongoing in an independent cohort of ~5,000 cancer pts from CCGA using an optimized assay; updated performance results will be reported. Conclusions: Cancers detected using WGBS of cfDNA had a worse prognosis than cancers not detected. WGBS cancer detection carried comparable prognostic significance as clinical stage. By preferentially detecting higher risk cancers, cancer detection using plasma cfDNA may avoid some of the overdiagnosis that has been seen with some existing cancer screening methods. Clinical trial information: NCT02889978.

2631 Background: Response to immune checkpoint inhibitors has been associated with immune activation and mutational load within a tumor. Previous results in other tumors have implicated MHC II protein tumor cell expression as a response predictor to immune checkpoint inhibitors. In the I-SPY 2 TRIAL, the anti-PD1 therapeutic antibody pembrolizumab (P) was available to HER2-negative subtypes and graduated in both the HR+/HER2- and TNBC signatures. Pre-specified biomarker analysis was performed to test tumor MHC II expression as a predictor of response to P in the I-SPY 2 TRIAL based on its central role in tumor antigen presentation. Methods: 156 patients (P: 67, controls: 89) had RPPA and pCR data. RPPA-based quantitative data for pan-MHC II protein isotypes HLA-DR/DP/DQ/DX and HLA-DR protein isotype was obtained from LCM-enriched tumor epithelium, and protein levels were assessed for association with pCR in the P and control arms separately using the Wilcoxon Rank Sum test (p < 0.05). Analysis was also performed in the HR+ and HR- subgroups. Markers were analyzed individually; p-values are descriptive and were not corrected for multiple comparisons. Results: Across all P- treated patients, the HLA class II molecules –DR and -DR/DP/DQ/DX had a positive association with response to P (p = 0.014 and p = 0.001). Expression of HLA-DR/DP/DQ/DX also had a positive association with response to P in HR+ tumors. Neither of these associations were seen in the control arm samples. Conclusions: The observation of elevation of MHC II protein expression in HER2- responding patients treated with P suggests that activation of antigen peptide exchange facilitated by these molecules in T and B cells may enhance response to P treatment.

Abstract Background Archived formalin fixed paraffin embedded (FFPE) samples are valuable clinical resources to examine clinically relevant morphology features and also to study genetic changes. However, DNA quality and quantity of FFPE samples are often sub-optimal, and resulting NGS-based genetics variant detections are prone to false positives. Evaluations of wet-lab and bioinformatics approaches are needed to optimize variant detection from FFPE samples. Results As a pilot study, we designed within-subject triplicate samples of DNA derived from paired FFPE and fresh frozen breast tissues to highlight FFPE-specific artifacts. For FFPE samples, we tested two FFPE DNA extraction methods to determine impact of wet-lab procedures on variant calling: QIAGEN QIAamp DNA Mini Kit ("QA"), and QIAGEN GeneRead DNA FFPE Kit ("QGR"). We also used negative-control (NA12891) and positive control samples (Horizon Discovery Reference Standard FFPE). All DNA sample libraries were prepared for NGS according to the QIAseq Human Breast Cancer Targeted DNA Panel protocol and sequenced on the HiSeq 4000. Variant calling and filtering were performed using QIAGEN Gene Globe Data Portal. Detailed variant concordance comparisons and mutational signature analysis were performed to investigate effects of FFPE samples compared to paired fresh frozen samples, along with different library preparations. In this study, we found that five times or more variants were called with FFPE samples, compared to their paired fresh-frozen tissue samples even after applying molecular barcoding error-correction and default bioinformatics filtering recommended by the vendor. We also found that QGR as an optimized FFPE-DNA extraction approach leads to much fewer discordant variants between paired fresh frozen and FFPE samples. Approximately 92% of the uniquely called FFPE variants were of low allelic frequency range (<5%), and collectively shared a “C>T|G>A” mutational signature known to be representative of FFPE artifacts resulting fromcytosine deamination. Based on control samples and FFPE-frozen replicates, we derived an effective filtering strategy with associated empirical false-discovery estimates. Conclusions Through this study, we demonstrated feasibility of calling and filtering genetic variants from FFPE tissue samples using a combined strategy with molecular barcodes, optimized DNA extraction, and bioinformatics methods incorporating genomics context such as mutational signature and variant allelic frequency.